Bag for at least partially enveloping a heart

ABSTRACT

A pouch to at least partly enclose a heart ( 1 ), the wall of the pouch ( 2 ) being elastic. The purpose of the pouch is to enclose at least part of a heart ( 1 ) and to oppose excessive dilation of the heart ( 1 ) that might be due to infectious disease of the heart muscle, for instance a viral infection or an autoimmune process. In many cases the use of such a pouch ( 2 ) may circumvent the need for a heart transplant.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application no.PCT/EP98/03619, filed Jun. 16, 1998, which application claims thepriority of German application no. 197 26 389.5, filed Jun. 21, 1997,and each of which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The invention relates to a bag, hereafter called pouch, withwhich to at least partly enclose a heart.

BACKGROUND OF THE INVENTION

[0003] Infectious disease of the heart muscle both by viral infectionand by autoimmune processes may lead to enlarged heart volume. If suchan enlargement exceeds a critical value, the result will be progressiveheart dilation which can be explained by Laplace's law. As the volumesubtended by the left heart chamber increases, the stresses in the wallsof this cavity will increase. Consequently the muscle fibrils areoverloaded and their ideal range of elongation is exceeded. When thisexcessive elongation takes place, there is, as a rule, a residual volumein the heart. Then the muscle fibrils must operate against a primarilyhigh wall strain, and are further extended thereby. A vicious cyclearises, leading to increasing distension of the heart and consequentheart insufficiency.

[0004] It is basically feasible to treat such a development in its earlystages by medicinally lowering the initial load by ACE inhibitors,however such treatment is not always successful. Moreover, on account ofinitially slight clinical effects, the status will be noticed many timesonly when a critical point already has been passed. In that case only aheart transplant can be resorted to.

[0005] The German patent document U1 295 17 393 discloses a pouchdefined in the preamble of claim 1; this pouch however is inelastic andserves to prevent myocardial dilation by the end-diastolic pressure.While this known pouch does prevent cardiac wall distention, it deliversthis effect impulsively once the heart volume equals the volume enclosedby the pouch. This impulsive effect adversely affects the heart.Moreover pleats may form in the pouch when the heart volume is less thanthat subtended by the size of the pouch.

OBJECTS AND SUMMARY OF THE INVENTION

[0006] The objective of the invention is to create a pouch with which toat least partly enclose a heart and opposing heart distention withoutthereby degrading heart function.

[0007] The problem basic to the invention is resolved by the disclosureof the characterizing part of claim 1.

[0008] The basic concept of the invention is to absorb in part thestrains in the wall of the hollow body foremost constituted by the leftheart chamber and to relieve thereby the myofibrils. This general effectalone already may prevent enlarging the heart volume beyond a criticalvalue. Accordingly the pouch of the invention offers a support role.

[0009] The elasticity function of the invention may be implemented in anumber of ways. A very simple implementation calls for the pouch alwaysexerting the same force on the heart regardless of the pouch'selongation, as a result of which the heart, regardless of its volume,shall always be relieved at substantially the same strain. In anotherappropriate embodiment of the invention, the pouch wall is elastic,whereby the stress it exerts and hence the relief of the heart increaseswith volume. The characteristics of elongation may be altered dependingon the desired relief. Appropriately for instance the pouch wallelasticity decreases with increasing stretching in order to account forthe specific strain in the heart wall. Advantageously too, saidstretching shall be bounded by a limit value at which the heart nolonger can enlarge. Contrary to the known pouch, this limit value cannotbe reached impulsively, but because of the elasticity of the pouch ofthe invention, can be reached only gradually, as a result of whichimpulsive pouch actions are precluded. The pouch limit valueappropriately shall be at a pouch volume corresponding to the heartvolume at maximum diastolic filling. On the whole, therefore, the kindof elasticity and the shape of the stretching curve of the pouch allowsdetermining and adapting the myofibril relief implemented by this pouch.

[0010] To mount the pouch in place, it can be thorascopically opened andthen be drawn over the heart muscle. This motion illustratively proceedsto the anulus fibrosus, that is, the valve plane, where the pouch shallbe fixed in place.

[0011] In a further embodiment of the invention, the volume of the pouchin its unstretched state is less than the volume of the heart in thestage of minimum filling. As a result, the pouch shall reliably restagainst the heart in all stretching phases.

[0012] If, as in one embodiment of the invention, the pouch wall iselastic and the stretching is bounded by a limit value, thenadvantageously the pouch shall be made of an elastic and of an inelasticmaterial. In this case the elastic material determines the stretchingfunction, whereas the inelastic material determines the stretching limitvalue. Appropriately in practice, the elastic material is made of athreaded sheet or fabric or knit into which are integrated threads madeof a substantially inelastic material. The substantially spatiallyinelastic threads appropriately are longitudinally displaceable in thesheet or fabric or knit.

[0013] In this embodiment it is especially-advantageous that thesubstantially inelastic threads be guided segment-wise out of the pouchand in this manner are adapted at maximum diastolic filling by beingsegment-wise knotted in length and volume to the shape and/or volume ofthe pouch. In this process the substantially inelastic threads runappropriately from the edge of the pouch aperture to a substantiallyopposite tip of the pouch. The threads then can be guided out of thepouch in the zone of its tip.

[0014] As regards the embodiment wherein the pouch dilation is subjectto a limit value, the pouch appropriately consists of a fabric or knitmade of inelastic threads while however allowing bending and beingcrimped transversely to their longitudinal direction. This kind ofshaping allows determining the stretching function and the limit value.

[0015] Appropriately the pouch wall is a thermoplastic allowing simpleshaping of the pouch and adapting it to the shape of the heart, or itmay be made of a biological material, denatured bovine pericardium beingespecially suitable.

[0016] To implement permeability to gases, in particular oxygen, and toliquids, the wall of the pouch of the invention appropriately shall be anetting. Such netting appropriately may be made of an open-pore foam,for instance silicone foam. Such a foam assures highly uniform andgentle application of pressure to the heart muscle. Moreover such a foamis able to absorb a lubricant, for instance a serous liquid, thusproviding good slippage between pouch and pericardium. Appropriately thelubricant is biological and genetically engineered, hyaluronic acidbeing especially suitable. By introducing a lubricant beforehand intothe foam, good slipping properties are provided from the beginning andas a result primary, self-reinforcing irritation of the pericardiumshall be avoided.

[0017] If the wall of the pouch of the invention is a netting, then suchmay be formed as a perforated sheet. Such a sheet is able to transmitthe pouch pressure through a large surface to the heart.

[0018] The wall of the pouch of the invention also may be a fabric or aknit. In this manner the pouch's stretching behavior can be matched toany particulars within wide limits.

[0019] Regardless of the pouch wall netting being constituted by asheet, fabric or knit, appropriately an additional coating of open-porefoam shall be provided to assure uniform force transmission and alsoholding any lubricants.

[0020] If the elasticity of the pouch wall decreases as stretchingincreases, or if there is a limit value on stretching, then a specialembodiment of the invention provides that the pouch be composed of twokinds of plastic threads or fibers, one kind of higher, and preferablymuch higher shaping temperature than the other, one kind being elasticand the other kind relatively less, preferably much less elastic thanthe other. By using such differing fibers, it is possible tothermoplastically shape the pouch at a temperature at which the lesselastic or inelastic material remains permanently shaped at a givenshaping temperature, though not the more elastic material. The lesselastic or inelastic material in this manner determines the maximumpouch stretching whereas the elastic material, which shall return to itsinitial shape, applies constricting forces on the heart, below the shapedetermined by the less or inelastic material.

[0021] In another embodiment of the invention, the plastic used inmanufacturing the pouch is thermoplastic. This feature offers theadvantage that not only can the pouch be prefinished in simple mannerinto a given shape, but also that the pouch can be shaped duringsurgery, or its shape may be altered during surgery, in order to adaptthe dimensions so found to the parts of the heart to be enclosed.

[0022] In a further embodiment of the invention the foam is made ofsilicone.

[0023] The objective of the invention furthermore is to propose a methodfor manufacturing a pouch as defined in claim 1. This problem isresolved by making a mold in the shape of the heart part to be enclosedand in that a gas- and/or liquid-permeable sheet or a netting of knitconsisting of a thermoplastic is pulled over the mold while heated.

[0024] The structure of the mold appropriately is entailed or determinedby imaging the shape of the heart to be enclosed and in that the mold isproduced from this image. The image can be produced in arbitrary manner,for instance by x-rays or computer tomography.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention is elucidated further in relation to the drawings.

[0026]FIG. 1 shows a first embodiment of the invention,

[0027]FIG. 2 is a second embodiment of the invention, and

[0028]FIG. 3 is a third embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The drawing schematically shows a heart 1 partly enclosed by apouch 2 of which the wall consists of a netting 3. The pouch 2 reachesas far as into the zone of the anulus fibrosus, that is as far as thevalve plane, where it is affixed (omitted from the drawing) to the heartmuscle along a selvage 4. The netting 3 consists of elastic threads. Inthe unstretched state, the volume of the pouch 2 is less than the volumeof the heart 1 in the stage of minimum filling. As a result, the nettingshall rest against the heart 1 in all stretching stages.

[0030]FIG. 2 shows a second embodiment of the invention which is avariant of that of FIG. 1. Identical or corresponding components aredenoted by identical references. The difference is that threads 5converge from the selvage 4 into a central point 6, whereas threads 7run substantially circumferentially. Where they cross at points 8, thethreads 5 and 7 are connected to each other, either by being fused,bonded or by dipping the entire pouch 2 into a body of material, forinstance foam which shall subsequently solidify.

[0031]FIG. 3 shows an embodiment of a pouch 9 consisting of a knit ofthreads 10 running from a selvage 11 to a central point 12 where theyare bundled away at their ends 13 which, following application of thepouch 9, then can be tensioned or be knotted to one another in order tomatch thereby the pouch 9 to the shape and volume of the heart 1.

1. A pouch (2) enclosing at least partly a heart (1) characterized inthat the wall of the pouch (2) is elastic.
 2. Pouch as claimed in claim1, characterized in that the elasticity of the wall of the pouch (2)decreases with increasing stretching.
 3. Pouch as claimed in claim 2,characterized in that the stretching is bounded by a limit value. 4.Pouch as claimed in claim 3, characterized in that the limit value isset at a pouch volume corresponding to the volume of the heart in thestage of maximum diastolic filling.
 5. Pouch as claimed in claim 1,characterized in that the pouch volume in the stretched conditioncorresponds at a m maximum to the volume of the heart in the stage ofmaximum diastolic filling.
 6. Pouch as claimed in claim 3, characterizedin that it is composed of elastic and of inelastic material.
 7. Pouch asclaimed in claim 6, characterized in that the elastic material consistsof a sheet or a fabric or a knit consisting of threads into which areincorporated substantially non-elastic threads.
 8. Pouch as claimed inclaim 7, characterized in that the substantially inelastic threads areincorporated into the sheet or the fabric or knit in longitudinallydisplaceable manner.
 9. Pouch as claimed in claim 8, characterized inthat the substantially inelastic threads are guided each in by segmentout of the pouch and thus are adjustable in length by means ofsegment-wise knotting and in that the volume and/or the shape of thepouch can be matched to the volume and/or the shape of the heart atmaximum diastolic filling.
 10. Pouch as claimed in claim 9,characterized in that the substantially inelastic threads run from theaperture edge of the pouch to a substantially opposite pouch tip. 11.Pouch as claimed in claim 10, characterized in that threads issue fromthe pouch in the vicinity of its tip.
 12. Pouch as claimed in claim 3,characterized in that consists of a sheet, a fabric or a knit comprisingcrimps, a pleat, accordion geometry or the like.
 13. Pouch as claimed inclaim 3, characterized in that it consists of a fabric or knit ofinelastic but bending threads crimped transversely to their longitudinaldirection, in particular in wavy and/or sig-zag manner.
 14. Pouch asclaimed in claim 13, characterized in that the crimps are thermally set.15. Pouch as claimed in claim 3, characterized in that the pouch is madeof a knit and in that the knit's threads are inelastic but bending. 16.Pouch as claimed in claim 1, characterized in that the wall of the pouch(2) consists of plastic or a biological material.
 17. Pouch as claimedin claim 16, characterized in that the biological material is bovinepericardium.
 18. Pouch as claimed in claim 1, characterized in that thewall is in the form of a netting (3).
 19. Pouch as claimed in claim 18,characterized in that the netting (3) consists of open-pore foam. 20.Pouch as claimed in claim 18, characterized in that the netting (3)consists of a perforated sheet.
 21. Pouch as claimed in claim 18,characterized in that the netting (3) consists of a fabric or a knit.22. Pouch as claimed in claim 21, characterized in that the sheet or thefabric or knit is coated with open-pore foam.
 23. Pouch as claimed inclaim 2, characterized in that the pouch (2) consists of two kinds ofthermoplastic threads or fibers, one kind of which is of a higher,preferably substantially higher shaping temperature than the other kind,the one kind being elastic and the other kind being relatively lesselastic, preferably substantially less elastic.
 24. Pouch as claimed inclaim 23, characterized in that the plastic is a thermoplastic. 25.Pouch as claimed in claim 19, characterized in that the foam consists ofsilicone.
 26. Pouch as claimed in claim 19, characterized in that thefoam is a lubricant.
 27. Pouch as claimed in claim 26, characterized inthat the lubricant is a biological lubricant.
 28. Pouch as claimed inclaim 26, characterized in that the lubricant is genetically engineered.29. Pouch as claimed in claim 28, characterized in that the geneticallyengineered lubricant is hyaluronic acid.
 30. A method for manufacturinga pouch as claimed in claim 1, characterized in that a mold in the shapeof the article intended to enclose the heart is manufactured and in thata gas- and/or a liquid-permeable sheet or a netting or a knit made of athermoplastic is pulled over the mold and shaped while heated. 31.Method as claimed in claim 30, characterized in that the shape of theheart to be enclosed is imaged and in that the mold is made based onthat image.
 32. Pouch as claimed in claim 1, characterized in that thewall of the pouch is made of tetrafluoroethylene, in particular ofopen-pore polytetrafluoroethylne foam